This invention relates to glycidyl esters of alpha,alpha-branched saturated monocarboxylic acids containing a total of 5 to 18 carbon atoms.
Imidazole compounds having a secondary amino group in the ring and salts or adducts thereof have been proposed as accelerator; for epoxy resin/curing agent systems. U.S. Pat. No. 3,756,984 relates to the preparation of a whole range of adducts of mono- and polyepoxides with imidazoles having a secondary amino group in the ring and to the use of such compounds as curing agents, alone or in combination with other curing agents in epoxy resin compositions, particularly in molding powders or powder coating compositions. These described epoxy-imidazole adducts are in general good curing agents and accelerators for the anhydride curing of polyepoxides.
However, in certain epoxy resin systems, such as epoxy resin solventless prepreg matrix systems for fiber-reinforced composites, not any type of epoxy-imidazole adduct can be used effectively as a curing agent or accelerator. Such systems require an accelerator which is liquid at room temperature and which is effective in an amount of 0.75% and 10% by weight based on the total weight of the epoxy resin composition, in order to minimize plasticizing effects. Also in such applications, the epoxy resin/curing agent/accelerator system should have a long shelf life, good reactivity at elevated temperature and high glass transition temperature.
It is therefore an object of the invention to provide an epoxy resin-based composition which is useful in solventless prepreg applications.